Media trays for imaging devices, such as printers and photocopiers, are typically configured to accommodate various sizes of print media (e.g. paper, cardstock, etc.). To this end, most media trays include a moveable length edge guide and a moveable width edge guide. The length and width edge guides hold the media in a neat stack in a constant location, so that the position and orientation of the media stays substantially constant as the imaging machine draws sheets into the imaging mechanism.
Systems have been developed to automatically detect the size of print media that is in the tray, and provide this information to the imaging device or a computer associated therewith. Automatic detection of media size helps prevent certain types of imaging errors, such as printing a document on the wrong size media, or printing in the wrong location on the media. In many cases, automatic media size sensing is achieved using two sets of sensors—one set of sensors associated with the length edge guide, and another set of sensors associated with the width edge guide. This approach tends to be costly, includes many parts, and can reduce reliability. Additionally, some automatic media size sensing systems can have difficulty distinguishing between two media sizes that are close in length and/or width.